Electrons are much cleaner probes of nucleon structures than hadron beams. At the same time the electron scattering at large momentum transfer can be a source of considerable photon radiation, which can significantly distort the inferred nucleon structure if it is not properly accounted for. We present a factorized approach to semi-inclusive deep inelastic scattering, which treats QED and QCD radiation on equal footing and provides a systematically improvable approximation to the extraction of transverse momentum dependent parton distributions. We demonstrate how the QED contributions can be well approximated by collinear factorization, and illustrate the application of the factorized approach to QED radiation in inclusive scattering. For semi-inclusive processes, we show how radiation effects prevent a well-defined "photon-hadron" frame, forcing one to use a two-step process to account for the radiation. We illustrate the utility of the new method by explicit application to the spin-dependent azimuthal asymmetries.
Webinar at https://us02web.zoom.us/j/81572103194?pwd=eE1QVWZFc1hWbWszZ2N0RW1iWHFBZz09